1. Field of the Invention
The invention relates to novel polymer/polyol compositions that are reactive with polyisocyanates to produce polyurethane products. The invention also relates to novel methods for making such compositions and to methods for making polyurethane products therefrom.
2. Description of the Prior Art
Polymer/polyol dispersions have been and currently are being used in the production of polyurethane products. Such dispersions result in polyurethane products having a wide variety of desirable properties.
There are a number of prior art disclosures relating to the production of polymer/polyol dispersions including the Stamberger patents, U.S. Pat. Nos. 3,304,273; 3,383,351 and Re. 28,715 (reissue of U.S. Pat. No. 3,383,351); the Stamberger British Pat. No. 1,022,434; the Scharf et al. and Kuryla Canadian Pat. Nos. 735,010 and 785,835; the Pizzini et al. U.S. Pat. No. 3,823,201; the Ramlow et al. U.S. patent application, Ser. No. 431,080, filed Jan. 7, 1974; the Ramlow et al. patent U.S. Pat. No. 3,953,393; and the DeWald U.S. Pat. No. 3,655,553.
Each of these prior art disclosures beginning with the Stamberger patents describes the production of polymer/polyol dispersions by polymerizing one or more ethylenically unsaturated monomers in situ in a polyol to form dispersions of small polymer particles dispersed in the polyol. The dispersions are then mixed with polyisocyanate and other polyurethane-forming reagents and reacted to form the polyurethane product and serve as a convenient, efficient and economical means for improving resultant polyurethane properties. This procedure and the resulting polymer/polyol dispersions have been widely accepted by the polyurethane industry and continue to be extensively used throughout the industry.
While the prior art polymer/polyol dispersions have found extensive use throughout the polyurethance industry, the development of more sophisticated, higher speed and larger volume equipment, machines and systems for handling, mixing and reacting the polyurethane-forming ingredients has created the need for improvements in polymer/polyol dispersions. The need for more stable dispersions has developed so that they can be stored until used without undergoing any significant settling. At one time there was not much concern for the seediness, viscosity or filterability of polymer/polyols in actual commercial practice. However, the state of the art of polyurethane production now has advanced to the point where these considerations are very important. There is now much concern with filterability, seediness, and viscosity because of the more sophisticated machine systems now in use for large volume production. Also, the prior art dispersions could not be made in highly stable condition with the relatively low molecular weight polyols such as dipropylene glycols, thus rendering the lower molecular weight materials less desirable than the higher molecular weight materials as a polyol component of polymer/polyol dispersions. The lower molecular weight polyols are of value in those instances where low viscosity is essential and for foams, coatings and some types of sealants.
The present invention provides highly stable and highly filterable polymer/polyol compositions which are low in, or substantially free of, seediness. It also permits comparatively higher polymer contents in the dispersion at lower viscosities without impairing stability. These and other advantages are obtained by employing in the lower molecular weight polyol a small amount of higher molecular weight polyol.
The use of polyol blends to produce polymer/polyols has been disclosed by the above-identified Stamberger, Scharf et al., Kuryla, Pizzini, Ramlow et al and DeWald patents and the Ramlow et al patent application. The use of low molecular weight polyols in polymer/polyol dispersions is mentioned in the Stamberger British patent. However, nowhere in any of these references is there any disclosure or suggestion of the discovery of the advantages of the present invention by the addition of a small amount of a higher molecular weight polyol to a lower molecular weight polyol as described and claimed herein.
The DeWald patent discloses that the polyol is preferably a triol but can contain as much as 40 percent of a diol or tetrol having the same molecular weight range. The molecular weights of the polyols do not exceed 5500, are preferably no more than 5000 and are advantageously in the range of 1500-5000 and preferably 3000-5000.
The Pizzini patent discloses the use of a polyol blend consisting of two polyols having the same molecular weights. The Ramlow et al patent application discloses the preparation of polymer/polyol dispersions from polyol blends and vinyl or vinylidene halogenide monomers and alleges improvements in stability. The application states that it has been found that stable graft copolymer dispersions derived from vinyl monomers can be prepared at temperatures below 100.degree. C. and in the absence of auxiliary chain transferring agents if the monomer is vinyl chloride, vinyl bromide, vinylidene chloride or vinylidene bromide. The polymer/polyols prepared from halogenated monomers can interfere with the production of polyurethane products and in many cases are unacceptable for such use by forming acidic decomposition products which interfere with the catalyst.
The Ramlow et al. patent discloses the preparation of polymer/polyol dispersions by polymerizing vinyl monomers in the presence of alkyl mercaptans as chain transferring agents in specially formulated, unsaturation-containing polyols containing specified, and ostensibly critical, amounts of unsaturation. Such polymer/polyol dispersions are very limited in their applications in the polyurethane field because of the malodorous qualities of the polyurethane products made therefrom. This malodorous quality results from the alkyl mercaptan chain transfer agent required by the patent disclosure in the manufacture of the polymer/polyol dispersion rendering such products unacceptable to the consumer, especially, in such products as mattresses or arm rests, crash pads etc. The use of alkyl mercaptans as required by this patent also presents excessive processing problems due to the extremely offensive and powerful odor of the mercaptans and their ill effects on the workers producing or using the dispersions.
None of the prior art references mentioned above and no prior art is known which discloses, teaches or suggests stable polymer/polyols having the advantageous properties of the compositions of this invention prepared from ethylenically unsaturated monomers by the use of blends of a large amount of a lower molecular weight polyol and a small amount of a higher molecular weight polyol.